Regarding vehicle antennas, for example, a plurality of antennas for different frequency communications such as AM/FM radio, Vehicle Information and Communication System (VICS), GPS, television (VHF/UHF band), Electronic Toll Collection (ETC) system were necessary to be provided inside or outside a vehicle.
These antennas are preferably positioned as compactly as possible. However, if the antennas are too close to each other, the antennas interfere with each other due to electromagnetic coupling. These antennas may not properly work because of the effect of this interference. To avoid such an interference between antennas, the antennas had to be spaced apart from each other, or laid out appropriately.
The antenna and its relating device are connected together by a cable. Thus, if a plurality of wireless devices using different antennas coexist, the arrangement of cables may be complicated.
On the other hand, various frequency bands are used for wireless communications, such as mobile phones and wireless LANs, as well. In particular, Ultra Wide Band (UWB) communications which have been recently introduced use a very wide band of frequencies ranging from 3.1 to 10.6 GHz. Thus, wideband antennas which can cover the wide frequency band are demanded.
The UWB antenna shown in Patent Document 1 includes two planar antenna elements having a pointed shape, such as a rhombus, a square, and a rectangle. The two planar antenna elements are arranged symmetrically by bringing corners of the two planar antenna elements closer together. A cable is connected such that the corners function as feeding points. The other end of the cable is connected to an electronic circuit, such as a receiver.